Round balers generally have a bale forming chamber defined by a pair of opposing side walls associated with an array of side-by-side belts, transverse slats trained on chains, a plurality of rolls or a combination of these various elements, e.g., rolls and belts. During field operation, windrowed crop material such as hay is picked up from the ground and fed into a fixed or variable diameter chamber. The hay is then rolled into a cylindrical package, wrapped with twine, net or the like and ejected onto the ground for subsequent handling.
Because it is not uncommon for windrows of crop material to be uneven and typically narrower than the width of the bale forming chamber, it is necessary for the operator of some prior art balers to observe the shape of the bale being formed and weave the baler in a generally zigzag pattern to uniformly distribute hay across the bale being formed and thereby avoid poorly shaped bales. This approach relies on the experience of the operator to determine when to laterally shift the position of the baler. The lack of exactness, inability to observe the bale shape, reliance on operator skill and operator fatigue all contribute to the possibility of improper feeding causing misshaped bales.
In bales formed in belt type balers when a substantially uniform diameter is not maintained, improper tracking occurs resulting in belt jamming and damage. In addition, the uneven shape of the bale causes low density areas on the bale periphery which could result in premature deterioration of the bale during field storage, where it is exposed to weather extremes, i.e., the low density area does not shed water as well as an evenly balanced and uniformly compacted area.
Operators of present day balers of the various types mentioned above recognize the need to conveniently and consistently form bales having a substantially uniform diameter throughout their length. This is accomplished to a certain degree by utilizing monitoring methods to ascertain parameters that in turn are used in the control of functions that have a direct bearing on bale shape. A control technique of this type is embodied in the system disclosed in U.S. Pat. No. 4,748,801, issued Jun. 7, 1988, 1979 in the name of Ronald T. Sheehan, et al. This system includes bale diameter monitoring apparatus for alternately generating first and second signals in response to predetermined incremental expansion of the bale forming chamber. This enables the operator to position the baler to feed crop to one side of the bale forming chamber when one signal is generated and to position the baler to feed crop to the other side of the chamber when the other signal is generated.
In U.S. Pat. Nos. 4,224,867, issued Sep. 30, 1980 in the name of Melvin V. Gaeddert, et al, and 4,517,795, issued May 21, 1985 in the name of Gerald F. Meiers, similar prior art techniques are disclosed in which a monitor senses belt tension as a bale is being formed and generates signals to the operator directly related to relative diameters. This enables the operator to steer the baler in a manner that will feed crop material to the area in the chamber that is deficient.
In another technique, embodied in the apparatus disclosed in U.S. Pat. No. 4,686,820, issued Aug. 18, 1987, in the name of Bryan K. Andra, et al, belt tension is again utilized to generate a signal. Control apparatus responds to the signal to deflect crop material into one of three regions of the chamber based on diameter differentials.
In yet another prior art technique, embodied in the apparatus disclosed in U.S. Pat. No. 5,131,214, issued Jul. 21, 1992, in the name of Gary J. Vermeer, crop being fed is monitored to assist the operator in the formation of round bales. The monitor in this system comprises an interval timer which signals the operator to direct crop material to alternate sides of the baler at preselected time intervals.
The existing round baler monitoring techniques described above in conjunction with various prior art bale forming methods, either monitor the general bale diameter, relative diameters or the time interval during which crop is fed.